Apparatus for introducing sealant into a clearance between an existing pipe and a replacement pipe

ABSTRACT

Apparatus is provided for introducing sealant into a clearance between a replacement pipe 9 and an existing pipe 36 within which in use the replacement pipe 9 is located. The apparatus comprises a nose-cone 1 having a tubular body 6 for connection to the upstream end 8 of the replacement pipe 9, frangible means 20 in the form of a pop-out plug; pierceable metal foil; plastic film or membrane to seal the bore of the tubular body 6 and at least one non return valve 2 in the form of an elastic ring 2, rubber O-ring 40 or plug 52 and spring assembly 53 to permit the flow of sealant from the bore of the body 6 into the clearance 37 by way of the wall of the body 6 but to resist return-flow from the clearance 37 into the bore.

The present invention relates to an apparatus and method for introducingsealant into a clearance between a replacement pipe and an existing pipewithin which, in use, the replacement pipe is located.

UK Published Patent Application Nos. 2227071A and 2236158A both describemethods for replacing or relining pipes, particularly domestic gasservice pipes, with replacement pipes.

In the methods described, after the replacement pipe has been insertedinto the existing pipe, any clearance between the pipes is sealed with asealant of a flowable, settable kind such as grout or an anaerobicsealant or any other suitable kind of sealant.

The sealant is injected into the downstream end of the clearance via asuitable fitting, it being understood that the terms "downstream" and"upstream" are used in relation to the normal direction of flow of gasin the existing service pipe from the main towards and into thepremises. The injected sealant travels upstream along the clearanceuntil it reaches the so-called "nose-cone". This is a component which isconnected to the leading end of the replacement pipe before it isinserted into the existing service pipe. The nose-cone has a tubularbody with a downstream portion connected to the upstream/leading end ofthe replacement pipe. Around the upstream portion of the body usuallyare means for sealing the clearance between the pipes when thereplacement pipe is located within the existing pipe. The sealing meansin the nose-cone are in the form of a flange or flanges or a vane orvanes and form a tight interference fit with the internal wall of theexisting pipe. It is these flanges or vanes which stop gas entering theclearance and also prevent the further progress of the sealant duringits journey along the clearance. The nose-cone also has a frangiblemeans to seal the bore of the tubular nose-cone body. This servestemporarily to prevent the ingress of gas into the replacement pipe.

When the sealant reaches the nose-cone, it is a signal that the entireclearance is occupied by sealant and that the clearance is completelysealed, the seal provided by the flange(s) or vane(s) not beingconsidered totally secure.

The distance between the downstream injection point in the clearance andthe nose-cone may be several meters as the distance will be equivalentto the length of service pipe being replaced. Clearly to fill the entireclearance a very large quantity of sealant is necessary and thisincreases the costs of these particular replacement methods.

It is therefore an object of the present invention to provide anapparatus and method for introducing sealant into the clearance betweena replacement pipe and an existing pipe in such a way that the quantityof sealant is reduced in comparison to the techniques described while asafe seal is still formed.

According to one aspect of the present invention, we provide apparatusfor introducing sealant into a clearance between a replacement pipe andan existing pipe within which in use the replacement pipe is located,the apparatus comprising a nose-cone having a tubular body forconnection to the upstream end of the replacement pipe, frangible meansto seal the bore of the tubular body and at least one non returnassembly means to permit the flow of sealant from the bore of the bodyinto the clearance by way of the wall of the body but to resist returnflow from the clearance into the bore.

Preferably the tubular body has a downstream portion for connection tothe upstream end of the replacement pipe and an upstream portionprovided with means for sealing the clearance between the pipes when thereplacement pipe is located within the existing pipe.

Suitably the wall of the body has at least one aperture and the assemblymeans comprises a valve. The valve may comprise resilient means adaptedin one position to close the or each aperture and in another position toopen the or each aperture if acted upon by sealant supplied above apredetermined pressure.

In one embodiment of the invention the resilient means comprises a ringof elastic material which is slipped over the body of the nose-cone tocover the aperture or all the apertures in the body of the nose-coneunless acted upon by the sealant.

In another embodiment of the invention the resilient means comprises aplug and spring against which in use the plug moves, the plug and springbeing located within the body of the nose-cone with the spring locatedbetween the frangible means and the plug, the arrangement being that ina first position the plug closes the or each aperture in the nose-conebody and on being moved to a second position against the spring if actedupon by sealant supplied above a predetermined pressure, the plug opensthe or each aperture before returning to the first position under theaction of the spring with release of the sealant pressure.

The apparatus may further comprise means for supplying sealant to thenose-cone. In this case the sealant supply means may be a tube having anupstream end for releasable connection to the downstream portion of thenose-cone and dimensioned to be inserted into and be retracted from thereplacement pipe.

Preferably means are provided for releasably connecting the tube to thenose-cone, the means comprising a tubular liner for the nose-cone, theliner being adapted to be a close push-fit within the nose-cone andhaving at least one aperture in its wall, the aperture or each aperturein the liner corresponding with that or those as the case may be in thenose-cone when the liner is appropriately positioned within thenose-cone, the liner being internally threaded and the connecting meansalso comprising a nozzle for connection to the leading end of the tube,the nozzle being externally threaded for connection to the liner whosethreads correspond.

The means for sealing the clearance between the pipes in the nose-conemay comprise at least one vane or flange disposed around the wall of thenose-cone.

Preferably there are a plurality of vanes or flanges, the diameter ofthe vanes or flanges increasing in the direction of the downstreamportion of the body from the upstream portion.

Suitably the frangible means is a member in the form of a metal foil,plastics film or membrane which can be broken by a rod or the likeintroduced down the replacement pipe.

Alternatively and most preferably the frangible means is a member in theform of a plug in the bore of the nose-cone body, which plug can bepushed out by a rod or the like introduced down the replacement pipe.

Conveniently the frangible means or member is located at the front endof the nose-cone.

The nose-cone may be made of polyethylene and may be a moulding.

The nose-cone may be formed from the replacement pipe itself rather thancomprising a separate element thereof.

According to a second aspect of the present invention there is provideda method for introducing sealant into a clearance between a replacementpipe and an existing pipe within which the replacement pipe is located,the method comprising introducing the sealant into the clearance at anupstream point in the clearance and causing the sealant to flow to adownstream point in the clearance.

Preferably the sealant is injected at the downstream end of thereplacement pipe.

Suitably before the sealant is introduced into the clearance, theclearance is sealed at a point further upstream than the point at whichthe sealant is introduced.

Conveniently, during the introduction of the sealant, the upstream boreof the replacement pipe is temporarily sealed.

In one embodiment of the invention the sealant is pumped along a tube tothe point of introduction into the clearance, the tube being locatedwithin the replacement pipe.

Embodiments of the invention will now be particularly described withreference to the drawings in which:

FIG. 1 is an exploded side view of the components in one version of theapparatus,

FIG. 2 is a longitudinal section side view of the nose-cone assembly anda side view of the tube assembly before connection to the nose-cone,

FIG. 3 is a longitudinal section side view showing the nose-cone andtube assembly connected together and in position in the replacement pipebefore its insertion into the existing pipe,

FIG. 4 is a view similar to that shown in FIG. 3, the replacement pipehaving now been fully inserted into the existing pipe,

FIG. 5 is a view similar to that in FIG. 4, the arrows showing thedirection of movement of sealant along the tube assembly, nose-cone andinto and along the clearance between the pipes,

FIG. 6 shows the position after the sealant has entered the clearanceand the frangible means in the nose-cone has been removed,

FIG. 7 is a longitudinal section side view of another version of theapparatus, the position being similar to that shown in FIG. 4,

FIG. 8 is a view similar to FIG. 7, the position being similar to thatshown in FIG. 5,

FIG. 9 is a view similar to FIGS. 7 to 8, the position being similar tothat shown in FIG. 6,

FIG. 10 is a longitudinal section side view of yet another version ofthe apparatus the replacement pipe having now been fully inserted intothe existing pipe,

FIG. 11 is a view similar to FIG. 10, the arrows showing the directionof movement of sealant along the tube assembly, nose-cone and into andalong the clearance between the pipes, and

FIG. 12 shows the position after the sealant has entered the clearanceand the frangible means in the nose-cone has been removed.

Referring to FIGS. 1 to 9, the apparatus shown in FIG. 1 comprises anose-cone 1, a ring 2 of an elastic material to form the non-returnvalve means in the nose-cone 1, a tubular liner 3 for close push fittingwithin the nose-cone 1 and a nozzle 4 for fitting into the leading endof a tube 5 through which, in use, sealant is to be pumped to thenose-cone 1.

The nose-cone 1 is similar to those described in our published UK patentapplication No. 2227071A and is a moulding of a suitable plasticsmaterial such as polyethylene. The nose-cone 1 comprises a tubular body6 having a rear or downstream portion 7 for connection to the leading orupstream end 8 of a replacement pipe 9 which may itself be of a plasticsmaterial such as polyethylene. In this case the nose-cone 1 is connectedto the replacement pipe 9 by push-fitting the rear portion 7 of the body6 into the leading end 8 of the replacement pipe 9, there being alocating flange 10 around the wall 11 of the body 6 to act as a stop.However such a flange is not essential and may be omitted to reduce thecosts of production of the nose-cone 1. In addition, the nose-cone 1 maybe attached to the replacement pipe 9 in other suitable ways for exampleby an adhesive method or by fusing the members together.

The connection between the nose-cone 1 and the replacement pipe 9 mustbe secure enough to withstand disconnection by the pressure of sealant.

The nose-cone 1 also comprises an upstream or front portion 12 formedwith a plurality, in this case five, generally circumferentiallydisposed and radially directed annular vanes 13 to 17 which are spacedfrom each other and the diameter of which increases in a direction fromthe front to the rear of the nose-cone 1. The vanes have front orupstream surfaces 18 which taper towards their periphery so that theycan flex more easily in use as shown particularly in FIGS. 4 to 9. Themost-rearward or downstream vane 17 is bolstered by a flange 19 tosupport it in use.

Closing the bore of the nose-cone 1 at its front or upstream end is afrangible means 20 which is in the form of a pop-out plug but could bein the form of a metal foil or a plastic film or membrane. The plug,foil, film or membrane are strong enough to resist the pressure offlowing sealant but can be displaced or burst as the case may be with arod. The plug, foil, film or membrane prevent the ingress of gas intothe nose-cone body and thence into the replacement pipe until the plugis removed or the foil or sheet broken.

Extending radially through the wall 11 of the body 6 in that portion ofthe wall 11 lying between the flanges 10 and 19 are a plurality, in thiscase four, apertures (only three visible in the drawings) 21 to 23 whichare circumferentially spaced by 90° from each other. These permitsealant entering the body 6 of the nose-cone 1 via the downstream end toenter the clearance between the pipes as will be described in moredetail subsequently.

The ring 2 of elastic material e.g. a very thin elastic band shown inFIG. 1 is slipped over the body 6 of the nose-cone 1 to rest between theflanges 10 and 19 as shown in FIG. 2 and cover all the apertures 21 to23 in the nose-cone body 6. The external diameter of the body 6 inrelation to the diameter of the ring 2 is such that the ring 2 isstretched tight across the apertures 21 to 23 to ensure they are closed.

The ring 2 forms a type of non-return valve which with appropriatedesign will permit the egress of pumped sealant from the nose-cone body6 into the clearance between the pipes but will prevent the return ofthe sealant from the clearance into the nose-cone body 6.

Referring to FIG. 1, the liner 3 comprises a tubular element which maybe of a metal such as copper. The rear or downstream portion 24 of theliner 3 is internally threaded for connection to the nozzle 4 of thesealant supply tube 5 as will be subsequently described.

Situated upstream of the threaded portion 24 are four apertures 25 to 27(only three shown) in the wall of the liner 3. These arecircumferentially spaced around the liner 3 at 90° angles and correspondto the apertures 21 to 23 in the nose-cone 1 although the apertures inthe liner 3 are larger than those in the nose-cone 1. The liner 3 is sodimensioned as to be a tightly fitting push-fit into the bore of thenose-cone 1 and the liner apertures are so positioned that they can bealigned with those in the nose-cone body as shown in FIG. 2.

The nozzle 4 shown in the drawings is of metal e.g. brass, and comprisesan upstream or front cylindrical portion 28 which is externally threadedfor threaded connection to the internally threaded bore of the liner 2as shown in FIGS. 3 to 9.

The nozzle 4 has a rear or downstream portion 29 of smaller diameterthan the front portion 28, which rear portion 29 is provided withseveral circumferentially arranged and sequentially disposed tooth-likeelements 30 to grip the internal wall of the tube 5 when, in use, asshown in FIGS. 2 onwards, the portion 29 is push-fitted within theupstream or leading end 31 of the tube 5. Separating the front and rearportions of the nozzle 4 is a flange 32 which serves to guide the nozzle4 when it is inserted into the replacement pipe 9 as exemplified in FIG.2, the flange 32 being a close but not tight fit in the pipe 9. Thenozzle 4 has a bore 5 extending through it, which bore 5 has acylindrical central portion 33 and outwardly tapering end portions 34and 35 which portions are clearly shown in FIGS. 3 to 5, 7 and 8.

The tube 5 itself may be of some suitable flexible hose material such asnylon and will have a smaller external diameter than the internaldiameter of the replacement pipe 9 to permit it (the tube) to be pushedfreely through the replacement pipe 9 and out of the other end thereof.

The existing pipe to be replaced may be a service pipe carrying gas orwater into a dwelling from a main. The pipe may be of galvanised steelfor example and may need to be replaced because it is leaking due tocorrosion.

In the first stage of a method for replacing a service pipe the tube 5is inserted into the rear end of the replacement pipe 9 and out of theother front end 8 of the replacement pipe 9. The replacement pipe 9 willhave already been cut to the appropriate length for replacement ofexisting pipe 36.

Next the rear portion 29 of the nozzle 4 is push fitted into the nowvisible upstream end of the tube 31 and the tube 5 and nozzle 4 areretracted a short distance into the replacement pipe 9 to the positionshown in FIG. 2.

In a further stage of the method the liner 3 is push fitted into thenose-cone 1 and the elastic ring 2 positioned over the apertures 21 to23. This position is also shown in FIG. 2.

In the next stage shown in FIG. 3, the nose-cone liner 3 is screwed ontothe threaded end 28 of the nozzle 4 at the same time causing the nosecone 1 to be push-fitted into the front end 8 of the replacement pipe 9.

Next the replacement pipe 9 is inserted nose-cone first into theexisting pipe 36 and pushed along it the desired length as shown in FIG.4 the vanes 12 flexing and sealing the now formed clearance 37 betweenthe pipes 9 and 36. While not shown, in practice the downstream end 38of the existing pipe 36 shown in the drawings would have already beendisconnected from the gas meter and would have been fitted with a glandthrough which the nose-cone and replacement pipe would be inserted sothat the gland formed with the replacement pipe 9 create a sealpreventing the escape of gas from the downstream end of the pipe 9. Thereplacement pipe 9 may be sufficiently long so as to reach theconnection of the existing pipe with the main several meters from thepoint of insertion.

There should be a sufficient length of tube 5 so that some protrudesfrom the back, downstream end (not shown) of the replacement pipe 9.This back end is connected to a conventional sealant injection gun (notshown). The components of the sealant which for preference is a two partanaerobic type sealant are mixed together and poured into the gun. Asshown in FIG. 5, the sealant is then forced by the gun along the tube 5into and through the nozzle 4 and then into the bore of the nose-cone 1where it impacts on and its further forward movement is arrested by thefrangible member 20.

If the sealant pressure is carefully selected, the sealant will now liftthe ring 2 as shown in FIG. 5 without breaking or displacing thefrangible member 20 and sealant will flow through the apertures 21-23into clearance 37 between the pipes 9 and 36. Injection is continueduntil a sufficient quantity has been injected into the clearance 37.When the sealant pressure is removed the ring 2 returns to its originalposition to stop the sealant 39 flowing back into the nose-cone 1 asshown in FIG. 6, the ring 2 serving as a non-return valve.

In the next stage as also shown in FIG. 6, the tube nozzle 4 isunscrewed from the nose-cone liner 3 by twisting the tube 5 and the tube5 and nozzle 4 are removed.

While not shown in FIG. 6, in the final stage of the process, to connectthe replacement pipe to gas, the downstream end of the replacement pipe9 is connected to the gas meter, the valve of which is closed and agland is fitted to the other side of the meter. A sharp pointed rod isthen inserted into the gland which seals the rod to the escape of gas.The gas meter valve is then opened and the rod is pushed through themeter and along the replacement pipe until the point of the rodencounters the frangible member 20 which by continued pushing of the rodis either broken or displaced as the case may be to permit gas to enterthe nose-cone 1 and thence the replacement pipe 9. Any remaining sealantin the bore of the nose-cone 1 will also be pushed out of the nose-cone.The rod is then withdrawn along the pipe 9, the meter and out of thegland and the meter valve is closed. The gland is then disconnected fromthe other side of the meter which is re-connected to the supply pipe.

Referring to FIGS. 7 to 9, the components and stages in the method areidentical to those shown in FIGS. 4 to 6 and similar items bearidentical reference numerals except that the elastic ring 2 has beenreplaced by a rubber O-ring 40 which is positioned to cover each of theapertures 21 to 23 as shown in FIG. 7 but which can be displaced by thepressure of the sealant as shown in FIG. 8 to permit the flow of sealantfrom the nose-cone 1 into the clearance by way of the apertures. Removalof sealant pressure causes the O-ring 40 to return to its originalposition to prevent the return of sealant from the clearance into thenose-cone. As with the elastic ring 2 the O-ring 40 serves as anon-return valve.

Referring to FIGS. 10 to 12, components similar to those in FIGS. 1 to 9bear similar reference numerals and will not be further described exceptfor any major differences.

The nose-cone 1 in FIGS. 10 to 12 as will be seen is not provided withthe flange 10 with which the nose-cones in FIGS. 1 to 9 are provided.The liner 50 is however significantly shorter than that liner 3 shown inFIGS. 1 to 9 and is not provided with the apertures shown in the linersin FIGS. 1 to 9. The liner 50 is however provided with a flange 51 atits rear end with which, in use, as shown in the FIGS. 10 to 12 the rearend of the nose-cone 1 engages, the flange 51 itself being retainedbetween the nose-cone 1 and the flange 32 of the nozzle 4.

In FIGS. 10 to 12 the non-return valve comprises a plug 52 and a spring53. The plug 52 is cylindrical in shape and is of metal e.g. steel. Thespring 53 is a conventional compression spring of spring steel. In usethe spring 52 is located between the frangible means 20 of the nose-cone1 and the plug 52 which, in use, locates at its other end against theupstream end of the liner 50.

The method of assembly of the components is similar to that previouslydescribed except that before the nose-cone 1 is attached to thereplacement pipe 9, the spring 53 and plug 52 in that order are insertedinto the nose-cone 1. As shown in FIG. 10, the spring 53 and plug 52 areso dimensioned that initially the plug 52 closes the apertures 21 to 23in the nose-cone 1. When sealant enters the nose-cone 1 via the tube 5and nozzle 4 it will move the plug 52 towards and against the spring 53if its pressure is suitably high enough so that the apertures 21 to 23are opened as shown in FIG. 11 to enable the sealant to enter and flowalong the clearance 37 between the pipes 9 and 36. When the sealantpressure is released, the plug 52 is moved towards the liner 50 by theaction of the spring 53 to close the apertures 51 to 53. After thesealant has set, the tube 5, nozzle 4 and liner 50 are then removed bypulling the tube 5 out of the replacement pipe 37 to leave the nose-cone1 and pipe 37 in situ as shown in FIG. 12. Otherwise all the other stepsin the method of replacement are similar to those previously describedin relation to FIGS. 1 to 9.

The method of pipe replacement described herein is very similar to thosemethods described in UK Published Patent Application Nos. 2227071A and2236158A and these documents should be consulted for more comprehensivedetails of the replacement method though this is not essential to theunderstanding of the present invention which is limited to the sealantinjection part of the prior methods and apparatus.

The amount of sealant used in this invention is very much reduced incomparison to the prior methods described above. In order to be sure oras sure as possible that the clearance between the pipes has been sealedit is necessary to ensure that the clearance area adjoining thenose-cone vanes is occupied by sealant. In the prior methods where thesealant is injected at the downstream end of the clearance, the sealantmust be pumped along the entire clearance to reach the vanes. Thusvirtually the entire clearance is occupied by sealant.

In the method of the present invention in contrast, since the sealant isactually injected through the wall of the nose-cone body, the sealantmust by definition be occupying an area of clearance adjoining thenose-cone valves. Therefore it is not necessary to fill the entireclearance to ensure that the clearance has been sealed.

I claim:
 1. Apparatus for introducing sealant into a clearance between areplacement pipe and an existing pipe within which in use thereplacement pipe is located, the apparatus comprising:a nose-cone havinga tubular body for connection to an upstream end of the replacementpipe, the tubular body having a downstream portion for connection to thereplacement pipe and an upstream portion provided with means for sealingthe clearance between the pipes when the replacement pipe is locatedwith the existing pipe, frangible means for sealing the bore of thetubular body, and at least one non return valve means for permitting theflow of sealant from the bore of the tubular body into the clearance byway of the wall of the tubular body and for resisting return flow fromthe clearance into the bore.
 2. Apparatus as claimed in claim 1, whereinthe wall of the tubular body has at least one aperture and wherein saidnon-return valve means, at one position thereof, resiliently closes theat least one aperture and, in another position thereof, resilientlyopens the at least one aperture when acted upon by sealant suppliedabove a predetermined pressure.
 3. Apparatus as claimed in claim 2, inwhich said non return valve means comprises a ring of elastic materialwhich is slipped over the tubular body of the nose-cone to cover the atleast one aperture in the tubular body of the nose-cone unless actedupon by the sealant.
 4. Apparatus as claimed in claim 3 in which saidnon return valve means comprises a plug and spring against which, inuse, the plug moves, the plug and spring being located within thetubular body of the nose-cone with the spring located between saidfrangible means for sealing the bore of the tubular body and the plug,such that in a first position the plug closes the at least one aperturein the nose-cone body and on being moved to a second position againstthe spring when acted upon by sealant supplied above a predeterminedpressure, the plug opens the at least one aperture before returning tothe first position under the action of the spring with release of thesealant pressure.
 5. Apparatus as claimed in claim 2 including means forsupplying sealant to the nose-cone.
 6. Apparatus as claimed in claim 5,wherein said sealant supply means comprises a tube having an upstreamend connectable to the downstream portion of the nose cone and beingdimensioned to be inserted into and retracted from the replacement pipe.7. Apparatus as claimed in claim 6, including means for connecting thetube to the nose-cone, the means for connecting the tube to thenose-cone comprising a tubular liner for the nose-cone, the liner beingclose push fittable within the nose-cone and having a wall including atleast one aperture, the at least one aperture in the liner wallcorresponding with the at least one aperture in the tubular body whenthe liner is fitted within the nose-cone, the liner being internallythreaded, the connecting means further comprising a nozzle forconnection to the leading end of the tube, the nozzle being externallythreaded for connection to corresponding threads of the liner. 8.Apparatus as claimed in claim 1, in which the means for sealing theclearance between the pipes comprises at least one vane or flangedisposed around the wall of the nose-cone body.
 9. Apparatus as claimedin claim 8, in which there are a plurality of vanes or flanges, thediameter of the vanes or flanges increasing in the direction of thedownstream portion of the tubular body from the upstream portion. 10.Apparatus as claimed in claim 1, in which the frangible means is onefrom the group consisting of a metal foil, plastic film and a membranewhich can be broken by a rigid element introduced down the replacementpipe.
 11. Apparatus as claimed in claim 1, in which the frangible meansis a plug in the bore of the nose-cone tubular body, which plug can bepushed out by a rigid element introduced down the replacement pipe. 12.Apparatus as claimed in claim 1, in which the frangible means is locatedat an upstream axial end of the nose-cone.
 13. Apparatus as claimed inclaim 1, in which the nose-cone is made of polyethylene.
 14. Apparatusas claimed in claim 1, in which the nose-cone is a molded body. 15.Apparatus as claimed in claim 1, in which the nose-cone is formed fromthe replacement pipe itself.
 16. Apparatus for introducing sealant intoa clearance between a replacement pipe and an existing pipe within whichin use the replacement pipe is located, the apparatus comprising anose-cone having a tubular body for connection to an upstream end of thereplacement pipe, sealing means for sealing the bore of said tubularbody and taken from the group consisting of a metal foil, a plasticfilm, a membrane and a plug sealing the bore of the tubular body, and atleast one non return means for permitting the flow of sealant from thebore of the body into the clearance by way of the wall of the body andfor resisting return flow from the clearance into the bore, wherein thesealing means can be broken or pushed out of the bore by a rigid elementintroduced down the replacement pipe.
 17. Apparatus as claimed in claim16, in which the tubular body has a downstream portion for connection tothe replacement pipe and an upstream portion provided with means forsealing the clearance between the pipes when the replacement pipe islocated within the existing pipe.
 18. Apparatus as claimed in claim 17,in which said non return valve means comprise a ring of elastic materialwhich is slipped over the tubular body of the nose-cone to cover the atleast one aperture in the tubular body of the nose-cone unless actedupon by the sealant.
 19. Apparatus as claimed in claim 17, in which saidnon return valve means comprise a plug and spring against which, in use,the plug moves, the plug and spring being located within the tubularbody of the nose-cone with the spring located between the means to sealthe bore of the tubular body and the plug, such that in a first positionthe plug closes the at least one aperture in the nose-cone body and onbeing moved to a second position against the spring when acted upon bysealant supplied above a predetermined pressure, the plug opens the atleast one aperture before returning to the first position under theaction of the spring with release of the sealant pressure.
 20. Apparatusas claimed in claim 17, including means for supplying sealant to thenose-cone.
 21. Apparatus as claimed in claim 20, wherein said sealantsupply means comprises a tube having an upstream end connectable to thedownstream portion of the nose-cone and being dimensioned to be insertedinto and retracted from the replacement pipe.
 22. Apparatus as claimedin claim 21, including means for connecting the tube to the nose-cone,the means for connecting the tube to the nose-cone comprising a tubularliner for the nose-cone, the liner being close push fittable within thenose-cone and having a wall with at least one aperture, the at least oneaperture in the liner wall corresponding with the at least one aperturein the tubular body when the liner is fitted within the nose-cone, theliner being internally threaded, the connecting means further comprisinga nozzle for connection to the leading end of the tube, the nozzle beingexternally threaded for connection to corresponding threads of theliner.
 23. Apparatus as claimed in claim 16, in which the means forsealing the clearance between the pipes comprises at least one vane orflange disposed around the wall of the nose-cone body.
 24. Apparatus asclaimed in claim 23, in which there are a plurality of vanes or flanges,the diameter of the vanes or flanges increasing in the direction of thedownstream portion of the tubular body from the upstream portion. 25.Apparatus as claimed in claim 16, in which the sealing means are locatedat an upstream axial end of the nose-cone.
 26. Apparatus as claimed inclaim 16, in which the nose-cone is made of polyethylene.
 27. Apparatusas claimed in claim 16, in which the nose-cone is a molded body. 28.Apparatus as claimed in claim 16, in which the nose-cone is formed fromthe replacement pipe itself.